1. Field of the Invention
The instant invention relates generally to an apparatus for reducing the high dynamic torques required from the drive train to rotate an oscillating shaft, thereby reducing power consumption of the power supply unit and wear of the drive train. More specifically, the instant invention relates to a washing machine agitator which will reduce the dynamic torque required to produce its oscillating rotation.
It has been discovered that for a given stroke rate of a washing machine agitator, a sinusoidal agitator motion, as graphically viewed with respect to time, requires the lowest peak torque and drive power. Conventional transmissions used in washing machines do not, however, produce such wave forms. Instead, higher harmonics are produced at the end of each agitator stroke and require large torques from the power unit as well as the drive train.
The instant invention provides an agitator comprising a post and integral vanes which have a lower torsional resonant frequency than that of the agitator stroke rate. This results in lower torque requirements by isolating the transmission and the drive motor FROM THE HIGHER HARMONICS associated with the conventional washing machine transmissions.
2. Description of the Related Art
Previous attempts to isolate the higher harmonics associated with the conventional washing machine transmissions have complicated the manufacture of the agitator. FIG. 1 depicts the previous attempt at an agitator which would isolate higher harmonics. Agitator 10 comprises a single agitator post 12 connected to each agitator vane 14 only one of which is shown for sake of simplicity. The agitator post 12 and each vane 14 are each connected to skirt 16.
To lower the peak torque required by the agitator, each vane was undercut at its connection to the skirt 16 along a majority of that connection. This undercut 18 allowed each vane 14 the flexibility needed to isolate the drive transmission not depicted from the high harmonics typically associated with washing machine transmissions.
Problems arise, however, in producing the agitator 10 in an efficient and cost effective manner. The molding of undercut 18 prohibits the production of agitator 10 by a single-draw mold as is well known in the art. One of ordinary skill in the art of molding would recognize that the portion of the mold not depicted which would create a void of material to produce undercut 18 would prevent that: mold from simply withdrawing from the molded agitator 10. Agitator 10 therefore requires a multiple step molding process which significantly increases production costs.
Further problems arise in the application of agitator 10. Undercut 18 will, at times, capture an article of clothing between the vane and skirt. This may prevent the flex of the vane needed to lower the peak torque required and may further cause excess wear on the article captured. Lastly, items caught in undercut 18 may result in breaking or removal of buttons or other attachments to articles washed.
The principle object of the instant invention is therefore to provide a means to isolate a shaft which oscillates in an axially rotating manner from peak torques wherein said means can be fabricated by a single-draw mold.
It is a further object of the instant invention to produce the isolated shaft means in the form of an agitator for a washing machine.
It is a further object of the instant invention to reduce the power required to drive a washing machine agitator.
It is a further object of the instant invention to reduce the peak torque imparted to the drive shaft and the peak forces sustained by the transmission of the washing machine.